Removable blade drag bits



June 9, 1959 H. J. HAWTHORNE vlET A1. 2,890,020

REMOVABLE BLADE DRAGl BITS Original Filed NOV. 30, 1949 H 1, J Haufz'NV/NTORS mwhd Bg'rl 111. wml/ep IL MW TTORN E VS nited States Patent O 2,890,020 REMOVABLE BLADE DRAG Brrs Herbert I. Hawthorne and Earl M. Weaver, Houston, Tex.

Original application November 30,` 1949, Serial No. 130,191, now Patent No. 2,831,657, dated April 22, 1958. Divided and this application July 30, 1956, Serial No. 601,014

5 Claims. (Cl, Z55-61) .Y The limitations of size and adaptability to the purpose to which rotary. bits are put in actual use have always caused' such bitsto be discarded as impractical. Failure has come from mechanical weakness, manufacturing difficulties, or simply failure to understand the problems of drilling.

Those who more closely approached success in the development of a replaceable blade bit in the past were unable to .provide any means to drill a widevariety of formations, from soft shales to reasonably hard limestone.- The harder formations, and even dense shale, caused -such vibration and chattering of the bit that if it did not fail by breakage, then the parts were distorted to such an Vextent that they could not be further used without great cost of repair. These costs were suchl that no savings could be made either in the: manufacture or in providing ,economies to the user. Consequently the result was to revert back 'to the integral type of blade bit or to the welded-in blade drag bit. l'

, The use' of a; drag bit indrilling harder formations is 'o'nducive'to chattering of the bit upon the formation, and whena bit' is subject to this vibration itwill suffer high-mechanical 4stresses that break the parts and cause highstresses that eventually cause failurel by fatigue. And lit'willwear the parts to such an extent that failure will result, or it will cause the parts to be distorted so as tobecome loose, with resultant failure. The present invention seeks to eliminate lthe eiectsl of chattering so as to vprovide a structure which tends to continuously offset or counteract any effect of chattering sothat the parts arelconstantlyfurged to tightly wedged position bythe driving force of the rotating -drill bit acting upon the parts in order to maintain them Yin a very tight position. "An object' o'f the invention is' to provide` an arrangement of intertting and contacting parts whereby the bit body may receivethe shanks of the several, bit segments so that they may be laid thereon and firmly clamped in position by an overlying slidable collar which is urged in towedging' position to maintain the bit Shanks upon thebitbodybythe drive of the drill pipe, which imparts rotafiQn 1Q: the .bi'-` A further object of this invention is to provide a rotary drilling bit of theV type yhaving. detachable blades maintained on abit bodyby aclamping collar, a bit body having a cylindrical portion and to one end thereof a M y der 28 provided as `outstanding' on the bit shank 21.- I-n non-cylindrical portion, with blade shanks configured on an inner surface to engage both of said portions under action of the clamping collar.

Other and further objects of the invention will be readily apparent when the following description is con- "ice sidered in connection with the appended claims and accompanying drawings, wherein:

Figure 1 is a bottom plan view looking at a bit which has'been constructed and assembled in accordance with the invention; Figure 2 is a sectional view taken along the drill bitl assembly and illustrating the arrangement of the replaceable blades, the bit body, the clamping collar, the adapter sub, and the drill pipe;

Figure 3 is a section taken on the line 3 3 of Figure 2, and

Figure 4 is a section taken on the line 4-4 of Figure 2.

The present application is directed to certain improvements in structure by which the removable or replaceable blades of rotary bits are securely held in position; and bits constructed in accordance with the present disclosure have been made and satisfactorily used in large numbers. The bits of the presentinvention are related to those shown in Hawthorne patents, Nos. 2,615,684 and 2,666,622`

With reference to Figures l and 2, the general arrangement of structure will be observed. As seen in Figure l there has been provided a plurality of drag blades 2; three ofthese blades have been shown but it is to be understood that eithentwo-Way, four-way, or other multiple of the number of blades maybe provided. As seen in Figure 2, these blades have a substantially central bottom cutting edge 4, and the stepped-up cutting edge 5, each of such cutting edges having a reaming edge 6. Each of these blades'may have a back-up brace as shown at 7, which serves to support the cutting blade as it rotates in order to cut the earth formation.

Each of these blades is a segment of a circle, and together they comprise the composite blade 10, each blade 2 lhaving the cutting edges 4 and 5 thereon, and each blade 2 has a rounded portion 11, which extends upwardly at 12 andhas the outer edge of the wing cutter 13 merging therewith. Above the wing cutter 13 there has been provided a shank 15., The cross-section of this shank is substantially a segment of a circle as best. seen inFigures 3 and 4, and, vas seen in Figure l, each shank constitutes a one-third of a cylinder for a three-blade bit. Figures 3 and 4 are sections taken on the lines 3-'3 and 4-4 of Figure 2, and Figure 3 shows the transverse section through the cutter blade just below the shank portion, and shows the curved configuration of the blade portion 10, with a thickened area 16 forming the initial portion of the shank.

. The edges of these portions, at 18 and 19, are arranged to abut complementary portions on the adjacent blades so that the cross-sectionalarea of the three shank portions when taken as a Whole constitute a complete circle,

as seen in Figures 3 and 4. The Shanks 15 are thickened, as seen inFigure 4, and arrangedto have a curved inner peripheral surface 15a which is arranged to lie in close contact against the surface20 of the bit body 21.

The bitv body has a passage 22 therethrough for flush-v ing fluid, which will pass through the composite passageway 24, bestr seen in Figure 1, where the threey composite blade portions provide a central opening which is partially covered by the inner edges 25 vof the lower: cutter Iblades 4. v Particular attention is directed toa shoulder 27 on the insiderperiphery of each shank 15, because it isarranged to abut upon an associated complementary shoulthis manner when the three Shanks of the cutter blades are laid upon the bit body, the shoulders 27 and 28 will engage each other,as seen in Figure 2; so it might be said that the bit blades are hanging upon this shoulder.

The bit body 21 has a cylindrical portion 30 against which the inner periphery of the shanks are laid, and above this cylindrical portion the Ibit body is formed with a coarse thread 32, which is seen in Figure 2 as receiving an adapter sub 35, into which the bit body has been shown as threaded at 36. This adapter submay or may not have the radially extending reamer wings 38 thereon so as to maintain the size of the h ole which is being drilled by the bit or to stabilize the drilling action of the blades for maintaining a straight hole. These wings also serve to clean the walls of the hole of cuttings and to smooth off ragged projections protruding into the hole.

One of the essential features of the invention isv the clamping collar 40, which is slidably arranged upon the bit body 21 and has the upper cylindrical portion 41 and the lower internally tapered portion 42. This tapered portion 42 is arranged to abut against the complementary tapered portion 43 which constitutes the outer surface of the composite cylinder formed by the Shanks of the three bit blades.

As will be apparent from Figure 2 this collar 40 is slipped down over the =bit body until the tapers 42 and 43 come into engagement with each other so that the collar serves to center the Shanks of all of the bits and to clamp them rmly in position.

This clamping collar 40 has a square upper end or shoulder 45 which is arranged to abut the square shoulder on the lower end 46 of the adapter sub 35. In this manner it will be apparent that there will be a constant driving action by the adapter sub 35 against the clamping collar 40.

This driving action is obtained due to the rotation of the drill stern 50, which extends to the surface. This drill stem has a lower threaded pin end 51, which is received in the female thread or 'box members 52. in the upper end of the sub 35. The abutting shoulders 53l on the drill pipe and the adapter sub act as the driving,

surface.

As is usual, the drill pipe 50 is rotated in a clockwise direction, which will tend to make up the threadV 51, which is yusually a right-hand thread. This imparts a right-hand or clockwise rotation to the adapter sub 35 so that it makes up or screws onto the upper end of the bit body 20.

Thus it is apparent that once the replaceable blades are arranged-about the bit body and the clamping collar 40 dropped into position, that then the Shanks are firmly held against the bit body due to the wedging actionV of the co-operating tapered surfaces 42 *and 43.

Beyond cylindrical surface 30 of the bit body is a.

non-cylindrical portion which in the embodiment of Figures l-4 is characterized by flat portions 60, three of which are best seen in Figure 3. These flats are arrangedl to co-operate with a complementary ilatv surface 61 onV the inside of the shank 15. With this arrangement the Shanks are firmly held against rotational movement by the flat area held against vertical movement downwardly by the co-operating shoulders 27 and 28, and they are firmly held against upward movement by the co-operating taperedV surfaces 42 and 43 on the clamping collar and the outer periphery of the shanks.

It is believed that with the foregoing construction-it will be apparent that the blades are irmly locked in position, and in event of hard digging and, chattering of the bit the parts are so iirmly held together that thel blades land the body actl as an integral member land the blades do not become loosened, distorted, nor misplaced.

It will be bornen mind that in many drilling operations twenty thousand to thirty thousand pounds of weight are placed upon the drill bit, and 'it may be rotated at several hundred revolutions per minute, so that it is easy to see that a tremendous stress will be applied to the bit blades and to the structure by which these blades are heldin position.

It is to be noted that the iiat areas which are provided upon the bit body and the internal surface of the shanks are such that these flats will t together rand when clamped in position are substantially immovable one with respect to the other.

The arrangement of the removable blades provides for the passage of the drilling fluid from within the drill pipe through the bit and out into the well bore over the cutting faces of the blades in order that the cuttings may be washed away from the bit.

Each blade is made with a recess on its laxial face, which, by engaging the axial cutting face of an adjacent blade, forms a iluid port. Thus the eroding or cutting action of the circulating fluid is coniined to the removable blades, so that with the present goods being manufactured the problem of maintaining fluid ports of conventional bits is eliminated.

From the foregoing it will be understood how a novel arrangement of a cylindrical body portion and a noncylindrical body portion co-operate with the blade shanks and the clamping collar to iirmly secure the detachable blades yto the body. Various modifications of this structure will occur to others upon reading this disclosure and, therefore, it is intended that the scope of the prment invent-ion be not limited to the hereinabove detailed description, but only by the appended claims.

What is claimed is:

1. In a rotary drilling bit of the type having detachable blades maintained on a bit body byy a clamping collar which encircles at least a part of the Shanks of the blades; a bit body having a cylindrical portion and to one end thereof a non-cylindrical portion, and the blade shanks being configured on their inner surfaces to engageboth of said portions under action of said clamping collar, said bit body and said blade shanks having interengaging means therein for llimiting relative axial movement therebetween under action of said clamping collar.

2. A bit as in claim 1 wherein the non-cylindrical portion of the bit body is polygonal in cross-section.

3. A bit asin claim 1 wherein at least in one diametrical direction the dimension of the non-cylindrical portion ofthe bit body is greater than the diameter of the cylindrical portion so as to provide shoulder means therebet tween constituting the interengaging means on said bit body, the arrangement being such that-said non-cylindrical portion jointly restrains the blade shanks from rotational and axial movement on the body.

4. A bit as in claim 1 wherein the non-cylindricalportion is substantially of hexagonal cross-section.

5 A bit. as in claim 4 wherein the major diameters of the hexagonal portions are in excess of the diameter of the cylindrical portion of the body to provideshoulder means therebetween constituting the interengaging means on said bit body.

References Cited in the file of this patent UNITED STATES PATENTS 1,370,492 smith et a1. Mar. 1, 192i 1,736,504 Mosley Nov. 19, 1929 2,656,153 white occ. 20, 1953v OTHER REFERENCES H. I. Hawthorne, Inc. Bulletin 47-1, dated September' 1946, page 2. 

